sorry... i'm not specifically sure about that piece... if your saying it's ac/dc adapter i doubt there's a "grounded" adapter available... you might try lifting the ground (shield) on the guitar end of the cable...

dementedchord wrote: sorry... i'm not specifically sure about that piece... if your saying it's ac/dc adapter i doubt there's a "grounded" adapter available... you might try lifting the ground (shield) on the guitar end of the cable...

I'm sorry about my lack of knowledge, but what is the ground shield?

on a balanced cable there are three connectors... two of which are wires that carry the signal out of phase or inverted from each other if you will... the third is the shield (often a woven wire) that does double duty in that it also provides a ground as well as shielding the two conductors from any RF interference... it's most likely to be if not the actuall cause at least exacerbating your problem... i'm assuming that the "expression system" doesnt draw its power from the phantom on the pre...(a safe assumption...)

Also, are you simply plugging the guitar into the Firepod, or are you plugging it into an amp or other processor at the same time? If it's just the Firepod, then the other poster is on the right track, in that this is probably a mis-grounded signal between the box and the guitar. I couldn't find much concrete tech info on the Taylor site, regarding the balanced signal and the connections on the guitar's output. You might contact their tech support team an ask about the polarity of the output and compare that to the input on Presonus. I believe that's where the problem lies.
If,on the other hand, ARE connecting to another device at the same time, be sure that you have all related components are powered by the same circuit, so that there are no "ground loops" that could be at fault.